     ;; TODO: handle And within the Or patterns.
     (raise "Non-simple `or` clauses not yet supported." {:clause orc})))
 
+(apply-function-clause [cc function]
+  cc)
+
 ;; We're keeping this simple for now: a straightforward type switch.
 (defn apply-clause [cc it]
   (condp instance? it

     [datascript.parser :as dp
      #?@(:cljs
            [:refer
             [PlainSymbol Predicate Not Or Pattern DefaultSrc Variable Constant Placeholder]])]
     [honeysql.core :as sql]
     [clojure.string :as str]
     )
  #?(:clj
       (:import
          [datascript.parser
           PlainSymbol Predicate Not Or Pattern DefaultSrc Variable Constant Placeholder])))

;; A ConjoiningClauses (CC) is a collection of clauses that are combined with JOIN.
;; The topmost form in a query is a ConjoiningClauses.


    Pattern
    (apply-pattern-clause cc it)

    Function
    (apply-function-clause cc it)

    (raise "Unknown clause." {:clause it})))

